Heater connector



J1me 1953 B. R. coRsoN ETAL 2,641,728

HEATER CONNECTOR Filed Feb. 25, 1950 INVENTORS 50mm A. (UliJO/V 14. V.PLAT/TR Patented June 9, 1953 HEATER CONNECTOR Bayard R. Col-son,Fishkill, and A. V'. Platter, Poughkeepsie, N. Y., assignors toInternational Business Machines Corporation, New York, N. Y., acorporation of New York Application February 25, 1950, Serial No.146,332

3 Claims.

This invention relates to vacuum tubes havin indirectly heated cathodesand more particularly to a novel heater connector for use with asingle-helix type heater in such tubes.

The helix type heater must be electrically connected at each end topermit electrical current to pass through it. The temperature of theheater coil itself when passing current is very large as compared to itsnormal room temperature when not passing current. As a result tremendousexpansion and contraction of the coil, as the case may be, takes placeafter the change from the operating or non-operating condition. Inaddition to the helix type heater the invention is particularlyapplicable to the folded type heater having an odd number of legs andthe ceramic rod type heater.

. In the prior art the connection of each end of a heater coil to arigid member which does not expand and contract with the coil as itexpands and contracts has caused the tube to have a relatively shortoperating life because of the mechanical fracture of the heater coil.

It is a principle object of the invention to provide a novel heaterconnector for a helical type heater coil wherein tube failure because ofmechanical fracture of the heater coil is substantially eliminated.

Another object is to provide a novel heater connector wherein expansionand contraction of the heater coil due to the heating and coolingthereof respectively, is caused to occur in a predetermined directionsuch that the heater coil always remains substantially the same distancefrom the cathode in a transverse direction and the uniform heating ofthe cathode is substantially unaffected.

A further object of the invention is to provide a novel heater connectorfor a spiral type heater wherein expansion and contraction of the heateris permitted only longitudinally thereto.

A still further object is to provide a heater connector which permitsvirtually free expansion of the heater in one direction, protects theheater from shocks in all other directions, and is cheaply made withautomatic machinery.

Other objects of the invention will be pointed out in the followingdescription and claims and illustrated in the accompanying drawings,which disclose, by way of examples, the principle of the invention andthe best mode, which has been.

contemplated, of applying that principle.

In the drawings:

Fig. 1 shows a vacuum tube structure em- 5 bodying the invention,

Fig. 1a is an enlarged isometric View of the invention shown in Fig. 1,and

Fig. 2 shows diagrammatically the application of the invention to a tubeemploying two heater elements.

Briefly, the invention includes the connection of a spiral type heaterin the usual rigid man-. ner at one end and the connection of the otherend of the heater to a conductive member arranged in longitudinalalignment with the heater coil. A ribbon shaped connector is bent ateach end to form a right angle. One bent portion is welded to theconductive member so that the plane formed by the face of the ribbonconnector is substantially parallel with the plane of the transverseaxes of the conductive member. The other bent portion of the ribbonconnector is rigidly aflixed to another conductive member in the heatercircuit. The connector offers a Very high resistance to the transversemovement of the heater and a minimum resistance to its longitudinalmovement. As a result, when the heater expands and contracts due toheating and cooling it remains substantially the same distance in atransverse direction from the other tube elements. This structureeliminates the possibility of non-uniform electron emission from thecathode due to the non-uniform heating thereof and insures long tubelife because of the decrease in the mechanical fracture of the heateritself.

Referring more particularly to Fig. 1, the tube is the conventionalcylindrical cathode type and is mounted on a base In having a pluralityof conductive pins extending therethrough. The electrodes of the tubeare mounted between the spacers II and I2. Cylindrical cathode I3 issupported between the spacers II and [2 in any conventional manner. Thegrid l6 and plate I! are positioned outward from and concentric withcathode 13. The spiral heater I9 is supported within the cathode l3 by aconductive support '20 connected to pin 2|. The heater I9 is rigidlyconnected to support 20 in any conventional manner so that electricalcurrent is passed thereto through the pin 2 I.

The upper end of the spiral heater :9 is connected to a conductivesupport 22 arranged in longitudinal alignment with the heater IS. Thesupport 22 is connected at its upper end (not shown), in anyconventional manner to permit it to expand and contract longitudinallyas it successively heats and cools. The conductive member 24 extendingthrough and fastened to the spacers II and I2 is substantially parallelto 5 the heater l9 and. support 22. The lower end of member 24 isconnected through support 26 to the pin 28.

A conductive ribbonrshaped heater connector 30 is bent at each end toform substantially a right angle. One end of the connector is welded tothe support 22 and the other end to the member 24. This connectioncompletes the heater circuit.

The function of the connector may be more clearly appreciated from Fig.1a. It should be particularly noted that the face of the ribbon shapedconnector as is in a plane substantially parallel to the transverse axisof the support 22 and the heater i9. Hence, because of the geometricconfiguration the connector 38 ofiers high resistance to the movement ofsupport 22 in any transverse direction and offers a minimum resistanceto the movement of the support in a longitudinal direction. As a result,the expansion and contraction of the heater is and support 22 due to theoperation and non-operation of the tube is up and down respectively oris longitudinal. Repeated expansions and contractions of the heatertherefore permit it to remain everywhere the same distance in atransverse direction from the cathode. This eliminates nonuniformelectron emission from the cathode due to non-uniform heating. Thismovement also lessens overworking of the heater or mechanical fracturethereof. It has been found that the invention provides a tube having amuch longer life free of heater failures than tubes of the prior art.

The particular dimensions of the various elements employed will, ofcourse, vary in accordance with each particular tube designed. Itsuffices to state that the geometry of the heater [9, support 22 andconnector 39 are such that the connector permits relatively easylongitudinal movement of the heater and support.

Fig. 2 demonstrates diagrammatically one way of using the invention in atube employing two heater elements. The tube contains a support meanssuch as the horizontal bar, 35 welded to the vertical supports 3% and31. The members 38 and 39 are the respective heater elements of the tubeor members which expand and contract with the respective heaters. Theribbon shaped connector at is U-shaped at either end to fit over therespective heaters and is rigidly afiixed thereto. A center portion ofthe ribbon connector is welded to the bar 35 as shown, each portion ofthe connector extending from the bar to its respective heater and beingresponsive to the longitudinal expansion and contraction of that heaterindependently of the other portion of the connector.

While there have been shown and described and pointed out thefundamental novel features of the invention as applied to a preferredembodiment, it will be understood that various omissions andsubstitutions and changes in the form and details of the deviceillustrated and in its operation may be made by those skilled in theart, without departing from the spirit of the invention. It is theintention, therefore, to be limited only as indicated by the scope ofthe following claims.

What is claimed is:

1. In a vacuum tube having a spiral heater element fixedly connected atone end; a first conductive member connected to the other end of saidelement and extending longitudinally therefrom; a ribbon shapedconnector affixed at one end to said first member and extendingsubstantially perpendicularly therefrom and rigidly affixed at its otherend, the two faces of said ribbon shaped connector being in planessubstantially coincidental with a plane formed by the transverse axis ofsaid first member so that the expansion and contraction of said elementcaused I by the heating and cooling thereof is substantiallylongitudinal with said first member because said ribbon shapedconnector, due to its shape, offers the least resistance to thelongitudinal movement of said first member.

2. In a vacuum tube having a cathode and a heater element mounted inspaced relation thereto. a conductive member connected to one end ofsaid element and expandable therewith, a ribbon shaped connector rigidlyfastened at one end and welded to said member at its other end so thatsaid connector ofiers less resistance to the movement of said memberalong a preselected single path than along any other path whereby saidmember remains in substantially the same spaced relation to said cathodeirrespective of the expansion and contraction of said element.

3. In a vacuum tube having a heater element rigidly connected at oneend, a cylindrical cathode mounted in spaced relation around said heaterelement, a first conductive member arranged substantially parallel tosaid heater element and aifixed at one end, a ribbon shaped connectoraffixed at one end to said first conductive member and at the other endto the other end of said heater element whereby said connector becauseof its ribbon shape offers less resistance to the movement of saidheater element inone direction than in any other direction to ensurethat said heater will move only in said one direction as a result of theexpansionand contraction thereof BAYARD R. CORSON. A. V. PLATTER.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,936,069 Reid Nov. 21, 1933 2,016,152 Marden et al Oct. 1,1935 2,339,402 I-Ierzog Jan. 18, 1944-.

